1. Field of the Invention
The present invention relates to a bearing for a vehicle steering column, which supports a steering shaft within a housing for rotation about an axis and tiltable movement of the steering shaft relative to the axis.
2. Description of Related Art
Various kinds of bearings for a vehicle steering column are well known. Among them, bearings made of synthetic resin materials have been proposed. Such bearings made of resin materials are securely mounted to a housing of the steering column and support a steering shaft disposed substantially concentrically with the housing such that the steering shaft is smoothly tiltable and rotatable relative to the housing.
Japanese Utility Model Application First Publication No. 57-117273 discloses a bearing for a vehicle steering column, which is made of a resin material. The bearing is fitted to a lower end portion of a housing of the steering column. The bearing includes a cylindrical larger-inner-diameter portion with a flange and a smaller-inner-diameter portion with tongues. The flange is engaged with the lower distal end of the housing. The tongues are adapted to contact a steering shaft received into the bearing. The steering shaft is rotatably supported by the tongues in its normal operation and by the larger-inner-diameter portion upon causing a larger tilting movement relative to the housing. A projection extending outwardly from an outer cylindrical surface of the bearing is engaged in a hole formed in a cylindrical wall of the housing for securing of the bearing to the housing.
In conventional bearings of such a type, the formation of the projection-insertion hole of the housing deteriorates a cost performance. Further, upon assembling the steering column by fitting the bearing into the housing, operations for alignment and engagement of the projection with the hole are inconvenient.
Japanese Utility Model Application Second Publication No. 1-28338 discloses a bearing for a vehicle steering column, which is made of a synthetic resin material. The bearing is press-fitted to a lower end portion of a housing of the steering column. The bearing includes a bearing body and an elastic bushing engaged with the bearing body. The bearing body has tongues contacted with the steering shaft at inner peripheries thereof. A resilient ring is fixed onto the tongues to bias the tongues against the steering shaft. When vibration is applied to the steering shaft to urge the steering shaft onto the elastic bushing, the elastic bushing absorbs the vibration to restrain noise from being caused by abutment of the steering shaft against the bearing body.
In conventional bearings of such a type, there is a likelihood that a clearance is produced between a whole body of the bearing and the housing due to aging and deterioration of the resin material of the bearing with the elapse of time. The clearance influences securement of the bearing to the housing and thus retention of the steering shaft relative to the housing.